Highly fluorescent pyreno[2,1-b]pyrroles: first syntheses, crystal structure, and intriguing photophysical properties.

A series of pyrrole analogues of benzo[a]pyrene have been synthesized in which pyreno[2,1-b]pyrrole exhibits highly fluorescent properties in solution as well as in crystalline form even possessing strong pi-pi stacking. The pi-stacking-induced fluorescence spectral changes lead to future applications such as molecular recognition feasible upon chemical modification.